1. Field of the Invention
The present invention relates to a 50 pound thrust level gas turbojet engine combustor structure, and especially to a through flow annular combustor employed in a 50 pound thrust level turbojet engine, and meanwhile the finite space in the engine is employed sufficiently and the flame stable effect is preferred in the primary zone, moreover, the combustor liner wall is well protected using film cooling means.
2. Description of the Prior Art
The prior art 50 pound level turbojet engines were only developed by Sunstrand and Teledyne Cos. U.S. The features of the prior art engines are that: the compressor and turbine are adapted with a back to back structure. The rotor has a solid structure. Two bearings are located at the front and rear ends of the mono-rotor. Moreover, a single stage centrifugal type compressor, a single stage turbine, and a reverse combustor are adopted. Besides, the fuel atomizing system is an air blast atomizing system used by an engine with the same thrust level.
In the combustor, other than the reverse combustor, a fuel slinger combustor is used, which is designed dependent on the integrality and type of the engine. However, the prior art combustor has a complex structure, and is difficult in manufacturing. In order to match the requirements of the engine cycle and the requirement of thrust, the combustor has a large size and occupies a large space. Furthermore, the size of the engine is enlarged so that the wind surface of the engine is increased. This is a problem necessary to be overcome in design.
Moreover, in the fuel atomizing system, in prior art engine uses a airblast or slinger system. However, in use of the fuel atomizer, generally, there are foaming type atomizer, electrostatic atomizer, supersonic atomizer, pressure atomizer, rotary atomizer, air assisted atomizer and air blast atomizer, etc, which are used dependent on the requirements of design (such as cost, thrust, fuel flow, etc.). In general, in above atomizers, the pressure atomizer, rotary atomizer, air auxiliary atomizer and air flow atomizer are used in the combustor of an engine for atomizing fuel.
The prior art engine uses a air blast atomizing system in a high pressure environment. However, since the system has a complex structure, and is difficult to be manufactured so that the cost of the engine is increased. Moreover, for a small type engine, air blast system has a bad efficiency, especially, in lower speed operation (for example, actuating an engine, low speed operation, etc.). This will induce that the engine is not easily in starting.
Moreover, in the slinger atomizing system, the rotary atomizer is likely to be operated in high speed for presenting a preferred fuel atomizing effect. This will induce that the engine is difficult in operation, has a higher cost and is difficult in design.
For a detailed background of a 50 pound thrust level gas turbine jet engine combustor structure one may refer to Taiwan Patent Nos. 325096 and 154153.
It should be appreciated that in the basic requirement in the design of a combustor, a flame stabilization means should be applied in the primary zone at first, namely, in a reasonable burning time, the fuel will be consumed completely for releasing energy. The flame stable means will change with the operating conditions of the combustor so as to affect the operation range of the
Thus, from above description, it is apparent that the prior art design is primarily studied from the experience of the engine manufacturer. The difficult for actuating an engine or in slow fire reduction in the engine after ignition so that the turbine will suffer from an overheating environment may be improved by changing the atomizing system and ignition energy. However, this is not easily.
One object of the present invention is to provide a turbojet engine combustor with a 50 pound thrust engine (with an outer diameter of 5.2 inches).
Another object of the present invention is to provide a 50 pound thrust level turbojet engine combustor structure with a jet tube design so as to stabilize the recirculation zone and increase the penetration depth of the primary jets. Thus, the zone may move toward the outer liner.
A further object of the present invention is to provide a 50 pound thrust level gas turbine jet engine combustor structure having a straight type combustor. The 50 pound thrust level turbojet engine can be manufactured easily with a lower cost.
Another object of the present invention is to provide a 50 pound thrust level turbojet engine combustor structure, wherein as the engine is operated in lower speed, it has a good fuel atomizing effect.
Another object of the present invention is to provide a 50 pound thrust level turbojet engine combustor structure which can be assembled, maintained and updated easily.
Another object of the present invention is to provide a 50 pound thrust level turbojet engine combustor structure using the principle of aerodynamics for protecting the liner of the combustor effectively.
The other object of the present invention is to provide a 50 pound thrust level turbojet engine combustor structure, wherein a bidirection thin film cooling is used for protecting the liner wall of the combustor.
A structure of a 50 pound thrust level turbojet engine combustor being a through flow annular combustor is provides in the present invention, which comprises: a combustor outer liner, the jet holes arranged with equal circumferential space on the outer liner wall. Further, the inner surface facing the hot stream is formed with circular protrusions with respect to the air inlets so as to be formed as a thin film cooling means for protecting the outer liner. A round hole for receiving an igniting device is formed in a front end of the outer liner. There are 24 primary jets, 24 dilution jets and 24 dilution enhancement jet holes are installed at the front, middle and rear sections of the outer liner.
Twenty-four jet tubes with a length of 8 mm are installed in a primary jet hole for increasing the penetration depth of the primary jet and thus enhancing the recirculation in the primary zone in order that the flame in the primary zone moves to the outer liner to enhance the combustion load. Moreover, the jet tubes serves to cool the inner liner.
A combustor inner liner: A plurality of jet holes arranged with equal circumferential space are installed at proper positions on the inner liner. Further, circular protrusions are installed at a wall normal to the outer diameter with respect to the air inlets so as to be formed with a bidirection thin film cooling means and a one way thin film cooling means for protecting the outer wall of the liner.
A hub: The rear axial portion thereof is combined with the inner liner of the combustor. Besides, a circular flange is installed at the outer axial periphery thereof for combining and positioning the outer liner of the combustor. The front end of the circular flange is formed as a slope surface. The slope surface is installed with air inlets arranged with an equal circumferential space. The air inlets are extended axially to be formed as a penetrating air hole. Twelve round holes arranged with an equal circumferential space are installed between the circular flange and the rear axial portion of the hub for receiving atomizers. Moreover, the front portion of the hub is installed with fuel inlets and lubricated oil inlets.
The above outer liner of combustor, jet tubes, and inner liner of combustor and the designs of fuel atomizer and bidirection thin film cooling are formed as a 50 pound thrust level turbojet engine combustor structure of the present invention.
In the annular combustor of the present invention, in order to forming a flame stable means, a primary jet flow serves to build a recirculation region in the primary zone. A lower speed flow region is built so that the transfer of the fuel may be matched with the flow speed. Radial jet flow serves to provides a long residence time for droplet so that the fuel can be burned completely and has a best effect. The recirculation structure of the present invention is formed by a primary jet flow to jet vertically to the combustor. The size of the recirculation region is dependent to the strength thereof and the momentum of the jet flow. A large recirculation region implies that a great pressure reduction, the efficiency of the combustion system will become worse. A weak recirculation region causes a bad mixing of fuel and gas so as to affect the combustion efficiency. Of course, the performance of the combustor is not only dependent on the recirculation region. Another important point is the inject position the droplet. If the inject position of the fuel is not proper, the recirculation is possibly destroyed so that the fuel and air does not mixed sufficiently or the fuel droplet will impinge on wall surface and other problems. In the present invention, the positions of fuel atomizers are properly installed for solving these problems.